Acceleration control system



Jan-25, 1938.

G. w. BAUGHMAN ACCELERATION CONTROL SYSTEM- Original Filed June 12, 1954 2 Sheets-Sheet 1 Y E 3 Q E g an N @Q Nb mlllml' INVENTOR GEURGE W BAUGHMAN BY ATTORNEY Jan. 25, 1938. 2,106,474

cs. w. BAUGHM-A N ACCELERATION CONTROL SYSTEM Original Filed June 12, 1934 2 Shets-Sheet 2 g SPEED AND 5 VOLTAGE 5 A 59 v i :61 l V B TIME/ I RELAY I CUE'PENT X I 157 I, I

I INVENTOR l W W GEORGE w EAUGHMAN BY 1 HI ATTORNEY Cal Patented Jan. ;.1938

ACCELERATION CONTROL SYSTEM George W. Baughman, Edgcwood, Pa., assignor to The Westinghouse Air Brake Company, Wilmer-ding, Pa., a corporation of Pennsylvania Original application June 12, 1934, Serial No. 730,231. Divided and this application July 25,

1936, Serial No. 92,675

1; Claims. (01. 172-179) f My invention relates to an acceleration and deceleration control system for railway vehicles and is particularly adapted for use on vehicles In the case of vehicles driven by electric moelectors it is usual to provide a notching controller that is governed by a master controller,. and, when put into operation, automatically cuts out resistance from the motor circuit step by step until the motor is brought up to full speed. In order to provide against too great overloading of the motor it is desirable to provide means for limiting the rate of operation 01' the notching controller during acceleration of the vehicle. It is desirable, therefore, in many installations, to provide a retardation and acceleration controller for limiting the rate of change in speed of the vehicle both during startingand stopping.

It is an object of my invention to provide an acceleration and deceleration control system for limiting the rate of increase, and the rate of decrease, in the speed oi the vehicle.

It is a more specific object of my invention to provide an acceleration and retardation control system in which the limiting rate of change in the vehicles speed is controlled by an electrical Other objects and advantages oif my invention v will appear from the following description of a specific embodiment thereof when taken in con-' junction with the accompanying drawings in which l Fig. l is a diagrammatic view ,of circuits and apparatus comprising one preferred embodiment or the invention,

Fig. 2 illustrates a detail of the vehicle directional switch, and

Fig. 3 illustrates curves showing the operation of the acceleration and deceleration control relay and,

Figs. 4, 5, and 6 illustrate different circuit arrangements for controlling the energization of the acceleration and deceleration control relay.

Referring to Fig. 1 of the drawings, a motor circuit extends from an overhead conductor I through a trolley 2, contact member 3 of a circuit breaker 4, the driving motors 5 and 6, controliresistor 1, conductor 8, winding 9 of a current' limiting relay H to ground at -l2. The winding 9 actuates a core l3 of the current limiting relay ii that ismechanically connected to a core ll by a stem l5, and which also extends downwardly and is connected to a contact member l6. windings i1 and" are associated with the core ll of the relay, the winding ll acting when energized to bias the core ll downwardly against the upward movement pull of the core l3, and the winding [8 being so wound and connected as to have when energized a differential relation'to the winding Iii A master controller I9 is provided for controlling the operation of the driving motors 5 and '8, and comprises an acceleration handle 2| .for

operating the contact members 22 and 23. When operated toward the right from the position conductor 21 to the source oi energy. At the same time a circuit is completed from a source of energy through conductor 28, movable contactmember 23 actuated by the acceleration handle 2|, segment 29, conductor 3| to the winding or the circuit breaker 4, energizing the circuit breaker and operating its contact member 3 into a circuit closing position to complete a circult to the motors 5 and 6. are also completed from the conducting segment 29 through conductor 32, one circuit extending along conductor 33, contact member l8 ol-the Control circuits current limiting relay H, conductor 34, the winding of a holding magnet valve device 35 of the acceleration controller 30, and conductor ii to a source of energy. A second control circuit ex tends from the conducting segment 29, through conductors 32 and, the winding of the operating magnet valve device 39, and conductor ll windings Hand .18 determines the downward pull on the core it that is required to be over- I come by the upward pull of the core I2, energized by the winding 0, in order to move the relay contact member I8 to a circuit'interrupting position. The. above traced circuits completed through the contact segment 29 cause the ,valve parts of holding magnet valve 25 and the operating magnet valve device 30 to be actuated downwardly to their illustrated positions, thus causing operationgoi the acceleration controller 38.

The acceleration controller 30 also comprises a chamber a port 49 leads into the left end oi. the

piston chamber, a port 5i leads upwardly to an exhaust port 52 for connecting the left hand end of the piston cylinder with the atmosphere when the valve 41 is in its lower, or illustrated,

position, and a port It leads downwardly and connects with an inlet chamber 04 that is con-' nected by a pipe Bl to the reservoir 06. A spring 51 is provided in the inlet chamber 54 for biasing the valve 48 upwardly. The operating magnet valve device 30 comprises a casing enclosing an inlet valve chamber 00, containing the valve 50, and an outlet valve chamber 0i containing the valve 82. These two valve chambers are united by a port I from which branch port 04 leads into the left end of the piston chamber for supplying it with air under pressureirom the inlet valve chamber 50, or for. releasing air through the outlet valve chamber ll and exhaust port 65. A spring 8! is provided in the inlet valve chamber for biasingthe valves 50 and" engage the contact segments 01, 00, 00, Hand upwardly against the force or the operating magnet. The contact arm 48 carried by the pinion 45 is adapted when moved in a clockwise ,direction from its illustrated position to consecutively 12, thus completing circuits through conductors 13, I4, I5, I8 and I1, and conductor 18 to shunt increasing portions of the starting re-- 'sistor I from the motor circuit. when the motors 5 and 6 are not energized the contact arm 48 remains inengagement with a stop I! as illustrated, and upon operation of the acceleration controller to increase the speed of the motors I and 8 a stop 0| prevents the contact arm 46 from passing beyond the contact'segment 12.

A brake equipment is provided of the well known fluid pressure type and comprises a brake valve 82 operated by a handle 00 for connecting the reservoir 56 through pipes 84, 00, and the 5 brake cylinder pipe 88 to the brake cylinder 01 to apply the brakes, and for releasing air under pressure from the brake cylinder 01 through the brake valve 82 to the atmosphere in a well known manner to release the brakes. An application magnet valve device 00 is located, between the pipes 05 and 8S and is normally maintained in its open or illustrated position to permit tree flow of air between the brake valve 12 and the brake cylinder 81. A release magnet valve device 89 is provided and is normally maintained in its closed position in order to maintain pressure within the brake cylinder 81. The application magnet valve device 10 and the release magnet Walve device 89 are controlled by operation of an acceleration and deceleration control relay 9| one part of which is energized from an axle driven direct current generator 02 that is oper- II to controlthe rate of operation of the acceleration controller 36.

The application magnet valve device 00 comprises a casing 04 enclosing an inlet chamber 05 in the lower portion thereof from which a port 0'6 leads upwardly into an application valve chamber 91, and is adapted to be closed by the application valve 00 that is normally biased to its upper or open position by a spring 09 in the inlet chamber 05. An outlet port I M communicates from the valve chamber 91 with the brake cylinder pipe 00. The release magnet valve device 09 comprises a casing I02 having an inlet port I02 connecting the brake cylinder pipe 00 with a valve chamber I04 containing a valve I05 normally biased to its upper or closed position by a spring I" to close a port I0I communicating between the valve chamber I04 and outlet chamber I00 having exhaust port I00. The acceleration and deceleration control relay Si is provided with a fleld core structure III that is energized by windings H2 and Ill, that are connected in series in a circuit represented by conductors H4 and III and energized from a suitable source 01' direct current energy An armature core H0 is pivotally supported at IIT between the pole faces of the U-shaped fleld core I I I, and is energized by an armature winding III that is connected by conductors H0 and I2I to the secondary winding I22 of a transformer I20. A primary winding I21 0! the transformer I20 is energized from the armature winding I24 0! the axle driven direct current generator 92that is operated in accordance with the speed of the vehicle. The generator fleld winding I25- is enemitted from conductors I20 and I2I that are respectively connected to the contact plates I20 and I20 oi the vehicle directional switch 03 In the illustrated position of the switch 03 the I2 0 and I20 are in contact, respectively, with contact members I" and I36 thus reversing the direction of energization of the field winding I25 of the axle driven generator 02.

The vehicle directional switch 03 is actuated to one of its two operative positions by a U- shaped magnet I31 that is pivotally supported at I30, the open end of the U-shaped core being positioned upon opposite sides of a metallic flange I ll of magnetizable'material carried by a shaft I, as best shown in Fig. 2. The magiietic drag existing between the flange I and the U-shaped armature Ill causes the armature to be actuated in the one or the other direction in accordance with the direction of rotation of the shaft I, which may be an axle oi thewehicle or any shaft driven in accordance with speed of the vehicle.

The armature core II! of the relay 9| carries an arm I42, that is" normally biased to its central or illustrated position by the springs i4! and I44,

and at the outer end of which a contact member I4! is carried that is adapted to be actuated into engagement with acceleration control contact members I45 and I4I'or into engagement with deceleration control contact members I48 and I48. Upon engagement of the contact member I45 with the contact member I45 a circuit is completed from a source of electric energy through conductor I5I, contact members. I45 and I48, resistor I52, conductor I58, the

winding I8, and conductor I54 to the source of energy, thus energizing the winding II to partially neutralize the eifect of the winding II. Upon a further movement of the contact member I45 toward the left engagement is made between contact members I45 and I4! and thus completing a circuit through the coil I8, in shunt cordingly actuated downwardly to close the port;

96 and interrupt the flow of air through the brake valve 82 to the brake cylinder 81, thus preventing further increase in pressure in the brake cylinder 81. If the contact member I45 moves further toward the right it will engage the contact member I48 and complete a circuit through the conductor I55 and the winding of the release magnet valve device 89, thus forcing the valve I05 downwardly to open the passage through the port I01 and release air under pressure from the brake cylinder '81 through exhaust port I09 to release the brakes.

Operation of the relay 8| will be best understood by reference to Fig. 3 in which the curve A represents a speed-time curve of the vehicle and the curves B and C represent the current through the winding H8 01' the relay. The curve Amay be regarded also as representing ,the current.

through the armature winding I24 oi the acceleration generator 92 and the'primary winding I28 4 of the-transformer in Fig. 1. From the point I51 to the point I53 on the curve A the vehicle is accelerating at a uniform rate as represented by the straight line joining these two points. The direct current through the primary winding I23 of the transformer I will accordingly build up as shown by the curve A. The current induced in the secondary windingglfl of the transformer Iii) will build up to a value X, as shown by the curve B, at which value the current is maintained constant so long as the rate oi acceleration remains constant.

From the point I58 to I58 on the curve A the speed of the vehicle remains constant as does also the direct current through the primary winding of the transformer I20. Since the current the secondary "winding I22 of the transformer is dependent upon the rate of change of the pri "mar-y current, the current will drop to zero value represented by the downward sweep of the curve B and remain at zero until the rate of speed of the vehicle again changes.

i rom the point I59 to the point I6I' on the curve A the vehicle is represented as. decelerating at a uniform rate as indicated by the straight line between these two points. A current will accordingly build up in the secondary winding I22 of the transformer I20 as shown by the curve C to a value Y, dependent upon the rate of deceleration of the vehicle, and remain at that value so long as the rate of deceleration remains constant.

The curve C is similar in charatter to. the curve B except that it is on the other side of the zero line and represents the flow of current through the secondary winding III of the transformer and the winding II8 of the relay 8| in a direction opposite tothe ilowof current represented by the curve B.

During the acceleration period of the vehicle,

current flows through the winding I I8, as represented by curve B, causing a torque on the armature of the relay 8| that is proportional to the current value and which actuates it in'a counterclockwise direction to causelengagement of the contact I45 with the'contactmembers I46 and I" to close the circuit above traced. As soon as the vehicle reaches a constant speed the ener- P gization of the relay winding II8 ceases and the I relay armature H8 and the contact member I45 are actuated by the springs I48 and I44 to their 1 mid, or illustrated, positions. During the period of deceleration represented by the curve C, current will flow through the winding I I8 of the relay '8I in a direction to cause movement of the core I I8, and contact member I45, in a clockwise direction to close circuits through contact members I48 and I48 as above traced. The current values through the relay winding I I8 represented by the ordinates X and Y of the curves B and C, respectively, will be dependent upon the rate of acceleration or deceleration of the vehicle.

Since the direct current generator 92 is driven from the axle of the vehicle a reversal in the direction of operation of the vehicle will cause a reversal in the polarity or direction of current through the generator armature, unless the direction of energization of the field winding I25-is reversed upon reversal of direction of operation of the vehicle. In order to provide against such reversal of polarity of the generator 92, and to operation of the vehicle.

To summarize the operation of the acceleration and deceleration system as a whole, if the operator wishes to start the vehicle the acceleration handle 2! is moved toward the right to close a circuit through the contact member 23 and contact segment. it] for operating the circuit breaker i to its circuit closing position, thus completing a circuit through the motors 5 and 6, and, at the same time, completing a circuit through the winding oi the operating magnet valve device 39 and the holding magnet valve device 35 of the acceleration controller 35. The valves of the devices 35 and 3% are accordingly operated downwardly, the device 35 venting that portion of the piston chamher to the left of the piston assembly at through ports -59, iii and 52 to the atmosphere. The operating magnet valve device 39 cuts oil communication between the piston vchamber to the right of the piston assembly 43 and the atmosphere toward the left. The pinion 45 and contact arm 45 are accordingly movedin a clockwise direction to cut successive portions of the resistor 1 from the motor circuit and accelerate the motors 5 and 6. The motor current circuit includes the winding 9 of the current limitingrelay I I, which, upon the flow of a predetermined current therethrough, operates upwardly to interrupt a circuit through its contact member i6 and deenergize the winding of the holding magnet valve device 35.' The valve 48 is thus forced upwardly by the spring 51, closing the passage through the exhaust port from the left of the piston assembly 43, and supplying air to this portion of the piston chamber through pipe 55, valve chamber 41 and port 49, thus preventing further operation of the arm 46 in a clockwise direction until the holding magnet valve device 35 is again energized. The

current through the motor'circuit and the winding 9 of the current limiting relay required to operate the relay to deenergize the holding magnet 35 is determined by the energization of the relay winding I1 which is greater, the further the acceleration handle 2I is moved toward the right, thus cutting out of the circuit a greater portion of the resistor 25.

During acceleration of the vehicle the acceleration and deceleration control relay 9| is actuated 'in a counter-clockwise direction as above exof acceleration that is still larger than that determined by the relay iii, the contact member I45 thereof will be moved further toward the left, causing engagement between it and the contact member I41 to further increase the energization of the differential winding I8 of the relay II to more completely neutralize the effect of the winding I1, and to establish anew setting for the current limiting relay whereby it will open when a still smaller current flows through the coil 9.

Unless otherwise operated by the control relay 9I, the application magnet valve device 88 remainsin its open or illustrated position, and the release magnet valve device 88 remains in its illustrated or closed position. The operator may, accordingly, move the handle 83 of the brake valve 82 to supply fluid under pressure to the brake cylinder 81 through the open application valve device 88, or to vent air under pressure from the brake cylinder through the valve device in the usual way, the pressure being maintained in the brake cylinder by the release magnet valve device 89in its closed position. 11' the rate of deceleration of the vehicle is greater than that permitted by the relay 8| the contact member I45 will be moved in a clockwise direction to effect 1 seating of valve 98 in the application magnet -ther operation in a clockwise direction, to close a circuit to the winding of the release magnet valve device 89 and cause it to operate to vent 3.11 under pressure from the brake cylinder 81 to the atmosphere, thus releasing the brake, until the rate of deceleration of the vehicle has been reduced to a value suflicient to cause separation of the contact members I45 and I49.

Fig. 4 illustrates a second preferred cmbadiment of means for maintaining the acceleration and deceleration relay 9| energized in accordance with the rate of acceleration and deceleration of the vehicle. The transformer I20 illustrated in Fig. l is omitted from the circuit shown in Fig. 4 and a condenser I62 is connected in series circuit relation between the armature winding I24 of the axle driven direct current generator 92 and the winding II8 of the relay 9|. In this embodiment of the invention, while the speed of the vehicle increases between points I51 and I58 on the curve'A shown in Fig. 3, the speed and voltage of the generator 82 correspondingly increases causing acharging current to flow from the generator to the condenser I 62 in accordance with the curve B of Fig. 3. A counter electromotive force is built up on the condenser I62 that is equal and. opposite to the electro-motive force from the armature winding I24 of the generator 92. While the vehicle is operating at constant speed, as represented by the portion of the curve A between points I58 and I59, the voltage of the generator 92 and of the condenser I62 remains constant and there is no exchange of current between them. Energy remains stored in the condenser I62 as a result of the current shown by the curve B from the generator to the condenser. During deceleration of the vehicle this stored energy causes a discharging current to flow from the condenser I62 to the generator 92, which will be in the opposite direction to the charging current as represented by the curve C in Fig. 3.

The acceleration and deceleration control relay 9i illustrated in Figs. 5 and 6 corresponds to the relay illustrated in Figs. 1 and 4 and may be energized by means of the mechanisms illustrated in either of these figures. In Fig. 5 an adjustable rheostat I 63 is provided in series with the relay winding IIB for adjusting the degree of acceleration or deceleration that it is desired to permit. In Fig. 6 an adjustable rheostat 16:2 is illustrated in shunt relation to the relay winding H8 and a resistor I65 is also illustrated in series relation to the winding IIB which may be employed if desired. By the use of such resistors the relay 9| may be adjusted to permit any desired degree of acceleration or deceleration.

While I have illustrated and described certain preferred embodiments of my invention, it will be apparent that many modifications thereof will occur to those skilled in the art within the spirit of my invention, and I do not wish to be limited otherwise than by the scope of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In an acceleration control system for vehicles, an electric motor for driving the vehicle, an acceleration controller for automatically and progressively increasing the power supplied to said motor during acceleration thereof, a current limiting relay responsive to a predetermined current flow through said motor for temporarily interrupting the operation of said acceleration controller, and electroresponsive means actuated in accordance with changes in the speed of said vehicle for decreasing the setting of said limiting switch upon a predetermined rate of acceleration of the vehicle.

2. In an acceleration control system for vehicles, an electric motor for driving the vehicle, an acceleration controller for automatically and progressively increasing the power supplied to said motor during acceleration thereof, a current hicle for progressively changing the setting of said current limiting means to become operative at lower current values upon increasing acceleration 01' the vehicle.

3. In an acceleration control system for vehicles, an electric motor for driving the vehicle, an

acceleration controller for automatically and progressively increasingthe power supplied to said motor during acceleration thereof, a current limiting means responsive to a predetermined current flow to said motor [or temporarily interrupting I the operation of said acceleration controller, electroresponsive controlmeans for decreasing the setting of said current limiting means to operate at lower current values, a direct current generator operated in accordance with the speed of the vehicle, and means connected between said generator and said electroresponsive control 'means'for effecting a current supply thereto that is a measure of the rate of change in, the speed of the generator.

4. In an acceleration control system for vehicles, an "electric motor for driving the vehicle, an acceleration controller for automatically and progressively increasing the power supplied to said motor during acceleration thereof, a current limiting means responsive to a predetermined current flow through said motor for temporarily interrupting the operation of said acceleration controller, electroresponsive control means for decreasing the setting of said current limiting" means to operate at lower current values, a direct' current generator operated in accordance with the speed of the vehicle, means connected between said generator and'said electroresponsive control means for efiecting a current supply thereto that is a measure of the rate of change in the speed of the vehicle, and means for automatically maintaining the polarity of the generator independently of the direction of operation of the vehicle. I

5. In an accelerationcontrol'system for vehicles, an electric motor for driving the vehicle, an acceleration controller for automatically and progressively increasing the power supplied to said motor during acceleration thereof, current limiting means responsive to a'predetermined current flow through said motor for temporarily interrupting the operation of said acceleration controller, electroresponsive control means responsive to'vehicle speed changes for decreasing the setting of said current limiting means to cause it to operate at lower current values, and means for adjusting the sensitivity of the electroresponsive control means to change the permitted rate of acceleration of the vehicle.

6. In an acceleration control system for veincles, in combination, an electric motor for driving the vehicle, means for automatically increasing the power supplied to said motor during acceleration thereof, and means for limiting the acce1- eration of said vehicle comprising an electroresponsive control means, a direct current generator operated in accordance with thespeed of the vehicle, and means connected between said generator and said eleotroresponsive control means for efiecting the current supplied thereto that is a measure of the rate of change in the speed of the generator.

'7. In an acceleration control system for vehi cles, in combination, an electric motor for driving the vehicle, means for automatically increasing the power supplied to said motor during acceleration thereof, means for limiting the acceleration of said vehicle comprising an electroresponsive control means, a direct current generator operated in accordance with the speed oi the vehicle, means connected between said generator and said electroresponsive control means for eiiecting the current supplied thereto that is a measure 01! the rate of change in the speed of the generator, and means for automatically maintair'iing the polarity of the generator independently oi the direction of operation of the vehicle.

8. In an acceleration control system for vehicles, in combination, an electric motor. for driving the vehicle, means for automatically increasing the power supplied to said. motor during acoeler'ation'thereof, and means for limitingthe acceleration of said vehicle comprising an electroresponsive control means, a direct current generator operated in accordance with the speed of the vehicle, means connected between said generator- "and said electroresponsive control means for effecting a current supplied thereto that is a measure of the rate of change in the speed of the generator, and means for adjusting the sensitivity of the electroresponsive control means to change the permitted rate of acceleration of the vehicle.

'9. In an acceleration control system for vehicles, in combination, an electric motor for driving the vehicle, means for automatically increasing the power supplied .tosaid motor during acceleration thereof, and means for limiting the acceleration of the vehicle comprising an electionsponsive control means, a direct current generator driven in accordance with the speed of thevehicle for governing the operation of said'electroresponsive control means and arranged to deliver a voltage that is a measure of thespeed'thereof, means connected between said generator and said electroresponsive control means for effecting a current supply to said electroresp'onsive control means that is a measure "of the direction and rate of change of the generator, and means for automatically maintaining the polarity of the genera tor independently of the directionof operation of thevehiole.

10. In an acceleration control system for vehicles, in combination, an electric motor for driving the vehicle, means for automatically increas ing the power supplied to said motor during acceleration thereof, and means for limiting the acceleration of the vehicle comprising an electroresponsive control means, a direct current generator driven in accordance with the speed of the vehicle for governing the operation of said electroresponsive control means-and arranged to Iiliver a voltage that is a measure of the speed thereof, means connected between said generator and said electroresponsive control means for :i-ecting current supplied to said electroresponsive control means thatis a measure. the direction and rate of speed 01" the generator, and means ior adjusting the sensitivity of the electroresponsive control means to change permitted rate of acceleration the vehicle ii. In an acceleration control. system for vehicles, in combination, an electric motor for driving. the vehicle, means for automatically increasing the power supplied to said motorduring ac celeration thereof, and means for limiting the acceleration of the vehicle comprising an electroresponsive control means, a direct current generator driven in accordance with the speed of the vehicle for varying the operation of said electroresponsive control means, and arranged to deliver a voltage that is a measure of the speed thereof, and means connected between said generator and said electroresponsive control means for efiecting a current supplied to said electroresponsive control means that is a measure of the direction and rate of speed change 01' the generator.

12. In an acceleration control system for ve-- hicles, in combination, an electric motor for driving the vehicle, means for automatically increasing the power supplied to said motor during acceleration thereof, means for limiting the acceleration of the vehicle, electroresponsive control means for controlling the operation of said limiting means, a direct current generator driven in accordance with the speed of the vehicle for gov-' erning the operation of said electroresponsive means and arranged to deliver a voltage that is a measure 01' the speed thereof, and a condenser in series circuit relation between said generator and" said electroresponsive control means.

13. In an acceleration control system for vehicles, in combination, an electric motor for driving the vehicle, means for automatically increasing the power supplied to said motor during acceleration thereof, means for limiting the ac celeration of the vehicle, electroresponslve controlmeans for controlling the operation of said limiting means, a direct current generator driven in accordance with the speed of the vehicle for governing the operation of said electroresponsive means and arranged to deliver a voltage that isa measure of the speed thereof, and a transformer having its primary winding connected in circuit with said generator and a secondary winding connected in circuit with the winding of said electroresponsive control means. 7

14. In an acceleration controlsystem for vehicles, in combination, an electric motor for driving the vehicle, means for automatlcallyincreasing the power supplied to said motor during acceleration thereof, means for limiting the acceleration of the vehicle, electroresponsive means for controlling the operation of said limiting means, a generator driven in accordance with the direction and speed of the vehicle, means for controlling the energization of said electro- .responsive means from said generator whereby the direction of current flow therebetween is a measure of the direction of speed change of said vehicle and the degree of energization is a measure of the amount of such acceleration, and means for maintaining the polarity of the generator in the same direction irrespective of direction of operation of the vehicle.

- 15. In an acceleration control system for vehicles, in combination, an electric motor for driving the vehicle, means for supplying power to said motor, means for controlling the rate 01 acceleration of said vehicle comprising magnet valve devices for controlling the supply or power to said motor, a contact making electrically controlled torque relay for controlling said magnet valve devices and having a magnetic circuit comprising a polarized field portion and an armature portion, a winding for energizing said armature portion, a direct current generator operated in accordance with the speed of the vehicle, means connected between said generator and said electrically controlled relay for eiiecting a current supply thereto that is a measure of the rate of change in the speed of the generator, and means for adjusting the sensitivity of the relay to change the permitted rate or acceleration of the vehicle.

16. In an acceleration control system for vehicles, in combination, an electric motor for driving thevehicle, manually operated means for eiIecting the supply of power to said motor, means for controlling the supply of power to said motor comprising magnet valve devices and a contact making electrically controlled torque relay having a magnetic circuit comprising a polarized field portion and an armature portion, a winding for energizing said armature portion, a generator driven in accordance with the direction and speed of the vehicle, means for controlling the energization of the armature winding of said electrically controlled torque relay irom said generator whereby the direction of current flowtherebetween is a measure of the direction of speed change of the vehicle and the degree of energization is a measure ofthe amount of such acceleration, and means for maintaining the polarity of the generator in the same direction irrespective of the direction ofoperation of the vehicle.

17. In an acceleration control system for vehicles, in combination, an electric motor for driving the vehicle, means for automatically increasing the power supplied to said motor during acceleration thereof, means for limiting the acceleration of the vehicle, a contact making electrically controlled torque relay for controlling the operation of said last mentioned means, said relay having a polarized field portion and an armature portion provided with an energizable winding, a direct current generator driven in accordance with the speed of the vehicle and be- 1 ing arranged to deliver a voltage that is a measv ing the supply of power to said motor, a contact making electrically controlled torque relay having a field portion and an armature portion, said relayalso having an energizable winding or one of said portions, means controlled by said relay for controlling said magnet valve devices, a generator driven in accordance with the direction and speed of thevehicle, means for controlling the energization of said relay winding from said is in accord with the direction of speed change of the vehicle and the degree of energization of said winding is a measure of the degree of speed change of the vehicle, and means for causing said relay to exercise proper control over said magnet valve devices for either direction of travel 01 the vehicle.

GEORGE W. BAUGHMAN. 

